Method of and apparatus for bonding light-emitting element

Abstract

A light-transmissive support disk supports a tube for attracting an LED chip, and a light-transmissive electrically conductive film is disposed on the support base. The LED chip is electrically connected to a negative terminal of a DC power supply by the light-transmissive electrically conductive film. An imaging unit is disposed coaxially with the tube and has a CCD camera for capturing an image of a light-emitting state of the LED chip via the support disk and a cover member when the LED chip attracted by the tube emits light. The light-emitting center of the LED chip can be detected accurately, and bonded easily and highly accurately on a board at a desired position thereon.

What is claimed is:  
     
       1. A method of bonding a light-emitting element on a board at a predetermined position thereon, comprising the steps of: 
       picking up and temporarily holding the light-emitting element with a holder integral with a light-transmissive support member from an area in which the light-emitting element emits light;  
       energizing the light-emitting element to emit light;  
       imaging a light-emitting state of the light-emitting element using an imaging means to obtain an image of said light-emitting element through said light-transmissive support member when the light-emitting element is being held;  
       determining a light-emitting center of the light-emitting element based on the imaged light-emitting state; and  
       positioning and bonding the light-emitting element held by said holder on the board at a bonding position thereon based on the recognized light-emitting center.  
     
     
       2. A method according to  claim 1 , wherein the step of determining a light-emitting center comprises the steps of: 
       determining four sides of a light-emission image based on the imaged light-emitting state;  
       thereafter, determining points of intersection of said four sides; and  
       determining a light-emitting center based on a point of intersection of diagonal lines passing through said points of intersection.  
     
     
       3. An apparatus for bonding a light-emitting element on a board at a predetermined position thereon, comprising: 
       a light-transmissive support member having a holder integral therewith, for picking up and temporarily holding the light-emitting element from an area in which the light-emitting element emits light;  
       light-emitting means for energizing the light-emitting element held by said holder to emit light;  
       imaging means for imaging a light-emitting state of the light-emitting element, wherein said imaging is obtained through said light-transmissive support member when the light-emitting element is being held;  
       image processing means for determining a light-emitting center of the light-emitting element based on the imaged light-emitting state; and  
       a displacement mechanism for positioning the light-emitting element at a bonding position on the board based on the determined light-emitting center.  
     
     
       4. An apparatus according to  claim 3 , further comprising: 
       a light-transmissive cover member, said light-transmissive support member and said light-transmissive cover member jointly defining a suction chamber therebetween; and  
       a negative pressure source connected to said holder through said suction chamber.  
     
     
       5. An apparatus according to  claim 4 , wherein said holder comprises an electrically conductive tube, said electrically conductive tube having a joining member projecting through a through hole defined in said light-transmissive support member into said suction chamber, said joining member having an end fixed by an adhesive to a surface of said light-transmissive support member which faces said suction chamber. 
     
     
       6. An apparatus according to  claim 5 , wherein said light-emitting means comprises a light-transmissive electrically conductive film disposed on said surface of said light-transmissive support member which faces said suction chamber, said joining member being fixed to said light-transmissive electrically conductive film by an electrically conductive adhesive. 
     
     
       7. An apparatus according to  claim 5 , wherein said light-emitting means comprises an electrically conductive member connected to said joining member. 
     
     
       8. An apparatus according to  claim 5 , wherein said electrically conductive tube-has a tapered portion which is progressively smaller in diameter away from said light-transmissive support member. 
     
     
       9. An apparatus according to  claim 8 , wherein said light-emitting means comprises a light-transmissive electrically conductive film disposed on said surface of said light-transmissive support member which faces said suction chamber, said joining member being fixed to said light-transmissive electrically conductive film by an electrically conductive adhesive. 
     
     
       10. An apparatus according to  claim 8 , wherein said light-emitting means comprises an electrically conductive member connected to said joining member. 
     
     
       11. An apparatus according to  claim 4 , wherein said light-emitting means comprises a light-transmissive electrically conductive film disposed on a surface of said light-transmissive support member which is opposite to said suction chamber, said holder comprising said light-transmissive electrically conductive film. 
     
     
       12. An apparatus according to  claim 3 , further comprising: 
       a movable tube disposed coaxially with said imaging means, said light-transmissive support member being mounted on said movable tube;  
       rotating means for rotating said movable tube; and  
       moving means for moving said movable tube toward and away from said imaging means.  
     
     
       13. An apparatus according to  claim 12 , wherein said movable tube is rotatably supported by an air bearing.